TMS 2017 SAN DIEGO CALIFORNIA
The TMS ( The Minerals, Metals and Materials Society) annual conference was held in San Diego, California this year. Some of our faculty and students were able to attend the conference and give presentations on their current research projects.
TITLES AND ABSTRACTS FOR THE PRESENTATIONS MADE
‘Circular Economy – A pathway to resource Recovery and Recycling’
Diran Apelian (Alcoa-Howmet Professor of Mechanical Engineering, Worcester Polytechnic Institute
The 21st century will witness a major shift in the organization of global value chains. As Klaus Schwab, founder of World Economic Forum has stated, “This is the era in which virtual and physical systems of manufacturing will globally cooperate with each other in a flexible way.” In brief, this is the era of innovation. This presentation will highlight the context of the paradigm shifts we are witnessing, and propose pathways to move forward. Of particular focus will be the circular economy as the way to create value in waste streams and develop sustainable business models in order for the solutions to be feasible.
Operational and Economic Impact of Super Vacuum Die Casting Technologies:
Muhammad Farooq1, Randolph Kirchain1, Richard Roth1, Alan Luo2, Diran Apelian3, Andrew Klarner2, Joshua Curto3, Libo Wang3, Di Wu1
1Massachusetts Institute of Technology; 2The Ohio State University; 3Worcester Polytechnic Institute
Light weighting of manufactured components is a major driver to reduce carbon footprint and fuel efficiency. One approach is to have strong materials that can be used in thin sections. However, the wall thickness of castings is dictated not by performance requirements, rather by processing limitations. Super vacuum die-casting (SVDC) is a recent process development, producing thin walled cast components that are heat treatable. While such technologies add some cost directly, this may afford savings in reduced material requirements and changes in downstream processing. This paper will report on operational developments associated with the casting process (modifications of dies and process settings) as well as downstream heat treatment processing. Using both experimental findings as well as a numerical sensitivity analysis, the key drivers of cost and cost savings are discussed. Among the main findings of the study is that these SVDC technologies outweighs investments, operational, maintenance and heat treatment factors.
Recovery of Aluminum from the Secondary Aluminum Production Dust
Myungwon Jung, Brajendra Mishra
Secondary aluminum production has several advantages over the primary aluminum production, such as resource conservation and energy savings. For these reasons, aluminum is one of the most recycled metals worldwide. During secondary aluminum production, dust containing aluminum is generated in many stages, and it is usually landfilled in US. However, a proper handling of aluminum dust is required since it has flammable and irritant nature. In this research, aluminum recovery from the secondary aluminum production dust is investigated by hydrometallurgical processes. First, sodium aluminate solution is generated by sodium hydroxide leaching of secondary aluminum production dust. After that, aluminum in the leach solution is recovered as the aluminum hydroxide by adjusting the pH of the solution. Based on the results, the percentage of aluminum recovery from the leach solution is about 94% at pH 10.5.
Selective Reduction and Separation of Europium from Mixed Rare-earth Oxides from Waste Fluorescent Lamp Phosphors
Mark Strauss1; Brajendra Mishra1; Gerald Martins2
1WPI; 2Colorado School of Mines
Europium is a critical material required for LED, florescent lamps, and flat panel display production. The recycling of europium from waste lamp phosphors is an innovative method to supply europium for high technology applications. Waste phosphor powder from recycled lamps is retorted, sieved, and leached to produce a europium/yttrium leach solution. The separation of europium and yttrium from the pregnant leach solution is conducted by selectively reducing Eu(III) to Eu(II) via zinc powder and precipitating europium (II) sulfate from solution using sulfuric acid as the precipitating agent. After one stage of selective reduction and precipitation, the purity and recovery of europium (II) sulfate was greater than 95% and 80%, respectively.
Algorithmic Prediction of Bulk Properties from Powdered Feedstock Consolidated via Laser-assisted Cold Spray:
Aaron Birt, Diran Apelian
Laser-assisted cold spray (LACS) is a solid state supersonic powder deposition process wherein the powders are deposited onto a region of substrate heated by a laser. The process has high build rates, hard deposits, and is fairly cost-effective due to use of nitrogen as the carrier gas. All of these benefits are derived from a set of extremely complex impact phenomena including high strain, thermal gradients, material jetting, and supersonic gas exchange. As a result, predicting material properties based exclusively on a defined set of system parameters is extraordinarily difficult even for an experienced user. To combat this, research has begun focusing on a set of statistical algorithms that can handle complex, noisy, and limited data. Using data from input powders, substrates, and system parameters, these algorithms will be discussed regarding their ability to predict, with varying degrees of success, key resultant properties of LACS deposits.
SPG-19: Application of Computational Thermodynamics & Kinetics to Rare Earth Reduction in Magnesium Alloys
Kyle Fitzpatrick-Schmidt, Danielle Cote, Diran Apelian
Magnesium alloys are widely used in numerous applications due to their extremely low density. Through the addition of rare earth metals, the high temperature capabilities of magnesium alloys are increased by creation of thermally stable secondary phases. This research is focused on reducing the amount and number of rare earth elements used in these alloys, while simultaneously maintaining the high temperature capabilities and low density. Thermodynamic, kinetic, and strengthening mechanism models have been used to analyze the magnesium alloy EZ33A and seven new compositions with varied amounts of rare earths and additional elements. The theoretical analysis was followed by experimental investigation of the new alloy compositions.
SPG-24: Thermodynamic & Kinetic Model Application to Strengthening Mechanisms of Aluminum Alloys for Additive Manufacturing
Derek Tsaknopoulos, Danielle Cote, Richard Sisson, Victor Champagne
While gas-atomized powder has become a staple feedstock material for additive manufacturing, detailed understanding regarding the mechanical properties of the raw material is needed for superior process modeling. Focusing primarily on the yield strength of the feedstock powder, various strengthening mechanisms are considered for the contributions from solid solution strengthening, grain size strengthening, precipitation, and dispersion mechanisms. These equations utilize the quantified kinetic and thermodynamic outputs from modeling software Thermo-Calc, JMatPro®, and TC-PRISMA. The data from these models coupled with the strengthening contributions progress into a strengthening model that represents the overall strengthening influence of each mechanism for specified gas-atomized powders. The effectiveness of this strengthening model is determined using thermal, optical, and mechanical characterization methods.
A-89: Friction Stir Welding of Dissimilar Metals
Xiangbin Wang, Yi Pan, Diana Lados,
Friction stir welding (FSW) is a solid-state welding process that has demonstrated the ability to join both similar and dissimilar alloys, as well as materials unweldable by traditional fusion welding techniques. To develop a fundamental understanding of the process, it is imperative to establish relationships between welding parameters and weld quality, resulting microstructures, and mechanical properties. Dissimilar welds using multiple rotation and traverse speed combinations were produced using three heat treated wrought aluminum alloys (Al6061-T651, Al2024-T351, and Al7075-T735), located systematically on both advancing and retreating sides of the weld. Similar welds were also produced and characterized for comparison. Weld quality was first evaluated to assess and optimize the processing conditions. Further, microstructural changes were systematically evaluated and correlated with micro-hardness and tensile properties of the welds. FSW of Al6061-T651 to steel was also performed successfully, and the resulting microstructures and mechanical properties will also be presented and discussed.
Low Temperature Reduction of Hematite in Red-Mud to Magnetite
Red-mud, the residue generated from the Bayers processing of bauxite ore in Jamaica was subjected to a low temperature reduction process. Hematite (~60 m%) was reduced to magnetite employing a gas based mixture of CO, CO2 and N2 as a diluent. Extensive thermodynamic study was conducted to identify the stability region for magnetite. ‘Optimal conditions’ for the gas-phase reduction were determined to be: a processing temperature of 540oC ± 10C , partial pressures CO(g) and CO2(g) each of 0.070atm (bar) ± 0.001atm.(bar)/ inert diluent-gas: N2(g), for a conversion-time of 30min. Frantz dry and Davis tube magnetic classification was tried on the magnetite product. The magnetic separation tests were not successful in achieving a high grade of magnetite in the magnetic fraction. This finding was subsequently attributed to the discovery, via STEM imaging, of nanometer length-scales associated with the nascent crystallites of the entities, which are intrinsic to Bayer-Process precipitate
Hot-tearing of Multicomponent Al-Cu Alloys Based on Casting Load Measurements in a Constrained Permanent Mold
Adrian Sabau1; Seyed Seyed Mirmiran2; Christopher Glaspie2; Shimin Li3; Diran Apelian3; Amit Shyam1; J. Haynes1; Andres Rodriguez4;
1Oak Ridge National Laboratory; 2Fiat Chrysler Automobiles North America; 3Worcester Polytechnic Institute; 4Nemak Monterrey
Hot-tearing is a major casting defect that is often difficult to characterize, especially for multicomponent Al alloys used for cylinder head castings. The susceptibility of multicomponent Al-Cu alloys to hot-tearing during permanent mold casting was investigated using a constrained permanent mold in which the load and displacement was measured. The experimental results for hot tearing susceptibility are compared with those obtained from a hot-tearing criterion based temperature range evaluated at fraction solids of 0.87 and 0.94. The Cu composition was varied from approximately 5 to 8 pct. (weight). Casting experiments were conducted without grain refining. The measured load during casting can be used to indicate the severity of hot tearing. However, when small hot-tears are present, the load variation cannot be used to detect and assess hot-tearing susceptibility.
I-15: Friction Stir Welding of Wrought and Cast Aluminum Alloys: Heat Transfer Modeling and Process Optimization:
Yi Pan, Diana Lados, Xiangbin Wang
Friction stir welding (FSW) is a relatively new solid-state joining technique, which provides good weld properties and behavior, even without the need of post-weld heat treatment. Understanding and predicting microstructure evolution and mechanical properties in FSW is critical for high-integrity structural design and material-process optimization. Four aluminum alloys (wrought 6061 and cast A356, 319, and A390) have been investigated in both as-fabricated and pre-weld heat treated conditions using various combinations of rotation and traverse speeds. An original thermo-mechanical model was created to predict the thermal history, stress distributions, deformation rates, and velocity fields in FSW. Further, a methodology for evaluating and indexing weld quality was also developed and used to establish optimized processing domains for each material. Resulting microstructures, hardness/micro-hardness, and tensile properties were systematically evaluated and mechanistically correlated to morphological changes in grain structures, characteristic phases, and strengthening precipitates using both experimental characterization and thermo-mechanical model predictions.
Development of Polymer-based Composite Coatings for the Gas Exploration Industry
Brajendra Mishra, Ali Chaudhry
Inorganic oxides can be synergistically beneficial for organic coatings, if it has the ability to impart anti-corrosion ability and as an additive to enhance physical or chemical properties. The aim of this study was to evaluate the anti-corrosion ability of nano nickel zinc ferrite (NZF) in solution and paint film. Anti-corrosion ability of NZF extracts in 1 molar H2SO4 and 3.5 wt % NaCl were evaluated using electrochemical techniques (EC). Time dependent anti-corrosion ability of NZF/chlorinated rubber nano-composite coatings (0.1% -1.0% NZF) applied on carbon steel (CS) were characterized by EC such as open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic (PD). Characterization of corrosion layer was done by removing coatings after 216 hrs in 3.5 wt % NaCl. Optical microscopy, EC data suggests electrochemical activity by metallic cations on surface during corrosion process which results improvements in the anti-corrosion properties of CS.
Carbide Precipitation during Heating in Martensitic Steels:
Xiaoqing Cai, Richard Sisson
Martensitic steels must be tempered to increase their toughness and ductility. The tempering process requires heating from room temperature to the desired tempering temperature. In this presentation the effects of heating rates on carbide precipitate size distribution, chemistry and precipitate density will be discussed. As-quenched Martensite in AISI 4140 steel was heated to selected tempering temperatures in air furnaces as well as by induction. The heating times to tempering temperature vary from 20 minutes to 10 seconds. The experimental results are presented and compared to theoretical calculations based on heterogeneous nucleation theory and growth kinetics. The results for hardness measurements are analyzed using the Holloman-Jaffe parameter.
Microstructure Evolution, Tensile and Dynamic Properties, and Computational Modeling in Ti-6Al-4V and Inconel 718 Alloys Manufactured by Laser Engineered Net Shaping:
Yuwei Zhai1; Diana Lados1; Eric Brown2; Greg Vigilante2; Robert Warren1;
1Worcester Polytechnic Institute; 2Benet Labs
Laser Engineered Net Shaping (LENS) is a directed energy deposition process able to fabricate fully dense metallic parts. Applying LENS to structural components and repair requires a fundamental understanding of the microstructure, static and dynamic properties, and damage mechanisms of the LENS-fabricated materials. In this study, Ti-6Al-4V and Inconel 718 alloys were deposited using two laser power levels for each material, and investigated in both as-fabricated and heat treated conditions. The effects of processing parameters and heat treatments on microstructure and room temperature tensile and fatigue crack growth (FCG) properties were systematically studied. FCG tests (R=0.1, 0.8) were performed in different orientations with respect to the deposition direction, in order to establish the FCG mechanisms at the microstructural scale of the alloys at different growth stages, and further correlate them to the processing conditions using thermal simulations results. The findings will be compared and critically discussed for processing-microstructure-properties optimization.
A Microstructure-Sensitive Fatigue Crack Growth Study Based on Experimental Measurements and Computational Modeling in Al-Si Cast Alloys:
Tiantian Zhang, Anthony Spangenberger, Diana Lados
Fatigue crack growth (FCG) plays an important role in material/structural design and component lifing. Robust FCG models necessitate microstructure-sensitive experimental studies of the damage near the crack tip. In this regard, plasticity ahead of crack tip in hypoeutectic Al-Si cast alloys was captured using in-situ and ex-situ DIC, and its interactions with the microstructure were studied. The strain field was found to correlate with both location relative to the crack path and alloy’s characteristic microstructural features. The DIC allowed establishing relationships between crack tip plasticity, microstructure, and FCG rate, while measuring crack tip opening displacement at various growth rates. Compliance and a non-destructive evaluation method based on eddy-current detection were used to monitor FCG at all growth stages. Microstructural characterization was performed using optical microscopy and electron backscatter diffraction (EBSD). The experimental determinations were successfully used to validate a computational model developed to predict FCG in cast Al alloys.
Microstructures, Precipitation Sequence, and Hardening of Al-Mg-Zn Alloys with High Mg:Zn Ratio:
Yangyang Fan, Diran Apelian
Al-11Mg-2.4Zn alloy has a eutectic reaction: L→Al +T+β at temperature of 445°C. After solutionization at 435 °C, the eutectic T and β phases are mostly dissolved in aluminum matrix. The subsequent aging of the alloy at the temperature between 160 °C to 200 °C leads to the precipitation of T”, T’, and β’. The precipitation sequence is discovered to be: SSS → GP zone → T”→ clustered T”→ phase T’ phase; β’ precipitates are found to be coexisting with T’ phases when aging temperature is above 200°C. When specimens are aged at 160 °C for 12 hours, the optimized tensile properties was obtained, and microstructure analysis shows that a large amount of 5~30 nm in radius, full coherent L12 crystal structure T” precipitates are homogenously distributed in the grains and as well as in the grain boundaries.
Metallurgical Bond Formation During Multimaterial Metal Casting:
Carl Soderhjelm, Diran Apelian
Cast-in ferrous inserts in aluminum castings can be a powerful tool to locally improve properties such as wear resistance, corrosion resistance, heat transfer and strength. The interaction between the two metals can result in two distinct types of bonding, a mechanical bond interlocking the two metals and a metallurgical bond. A continuous metallurgical bond could have the potential to improve load and heat transfer across the boundary between the steel and the aluminum. The formation of a continuous reaction layer between the ferrous insert and the aluminum alloy is a diffusion process which requires both energy and time to grow. To practically apply this technology a better understanding and quantification of the conditions necessary for the formation of a continuous metallurgical bond and is the focus of this work. Results will be presented and discussed.
Electrospun Separators for Structural Battery Applications:
Wisawat Keaswejjareansuk, Jianyu Liang
Lithium-ion battery (LIB) has been utilized in energy storages and source. Structural battery is a new approach that employs multifunctional material concept to use LIB with load-bearing capability to minimize the weight of the complete energy consumption system and maximize the efficiency. Separator has been known as the weakest part of LIB. This work aims at creating electrospun polymer membranes with nanostructures as next generation LIB separator with improved properties. Electrospinning (ES) employs the electrostatic force to control the production of nanofibers from polymer solutions. Solution and process parameters, such as concentration of solution, ES voltage, and solution feed rate, have been studied to achieve the desirable membrane properties. In this study scanning electron microscopy, dynamic scanning calorimetry, tensile testing and electrochemical testing have been used to characterize the electrospun membranes. Design of experiments has also been utilized to optimize the parameters in creating an improved separator for structural batteries.
Microstructure Evolution, Fatigue Crack Growth Mechanisms, and Effects of Heat Treatment and HIP in Ti-6Al-4V Alloys Fabricated by Electron Beam Melting
Robert Warren1; Haize Galarraga1; Diana Lados1; Ryan Dehoff2; Michael Kirka2;
1Worcester Polytechnic Institute; 2Oak Ridge National Laboratory
Electron Beam Melting (EBM) is an Additive Manufacturing process that selectively fuses powder-bed particles using an electron beam as the power source. EBM can produce unique microstructures and mechanical properties which are related to the processes specific thermal history. In this study, Ti-6Al-4V alloys fabricated by EBM have been systematically investigated. The microstructures, tensile, and long and small fatigue crack growth (FCG) properties have been evaluated and compared in different orientations relative to the deposition direction. The effects of various heat treatments, Hot Isostatic Pressing (HIP), initial crack size, and stress ratio on the FCG mechanisms at the microstructural scale of the materials has been determined, and will be discussed from structural design perspective. Original analytical methods for FCG threshold correlations and computational modeling work for predicting temperature evolution during processing and microstructure development will also be presented and discussed for properties optimization and rapid qualification.